Simple homemade encryption algorithm

(Source code on request. UPDATE: See below)

Made an encryption scheme that creates a square (padding random bytes if necessary) and shifts a square based on the password. Given the same password, it will perform the same shifts. Decryption uses the same algorithm but performs the actions backwards.

Another version (shown second, starting at 0:53) also does character substitution. This basically adds up the values of each character of the password and each character of the data, modulus the length of the character set of course. After that it still performs shifting.

It's not going to be used for anything at all ("rolling your own" is always an extremely bad idea in cryptography, I know that very well), I just enjoyed creating it. Just shifting the square around seems to give a pretty random outcome, and with character substitution you really can't tell what the original was.

The algorithm also includes an extremely simple key derivation function which obfuscates the key input for a more random looking output (though the key needs not be fixed-length). It only accepts ASCII input, no accents or euro symbols or anything outside 32-127. It's not meant to be really used anyway. Again, source available on request. Note that I can't comment because then I'd need to make a Google+ profile, but I will read comments (typically within 24 hours, assuming I get an email notification) and simply edit the description to include a link.

SOURCE CODE

Update June 2018: Wow, I had no idea there were comments on this video at all. Everyone has been asking for years! Sorry!

http://lucb1e.com/rp/php/horrible-encryption-square.php

I have to warn you, it's not super easy to use. You need to have PHP installed on the command line (Ubuntu/Debian/Mint: apt install php-cli) and run it as shown in the video. To change whether it does substitution, see the third line of the file.